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From "Susan Cline (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-1804) [DOC] CAST conversions between data types table is incorrect in Reference manual in some VARCHAR and TIMESTAMP cases
Date Mon, 11 Sep 2006 18:53:23 GMT
    [ http://issues.apache.org/jira/browse/DERBY-1804?page=comments#action_12433931 ] 
            
Susan Cline commented on DERBY-1804:
------------------------------------

Hi Laura,

Whoa .. I think that I'm confused about how to read this table.  The way I was reading it
was down the column instead of across on the row.  This is my mistake and therefore the document
as it stands is correct. However, do you think it would be possible to make a change from
this:

The first column on the table lists the source types, while the first row lists the target
types. A "Y" indicates that the source to the target is a valid conversion.

to this: (or whatever you think clarifies how to read this table, and maybe it does not need
clarification, it might have just been my misread.):

The column on the table lists the source types, while the row lists the target types.
 A "Y" indicates that the source to the target is a valid conversion.
For example,  the source represented by the first column lists the target types in the first
row, the source represented by the second column lists the target types in the second row
and so on.

> [DOC] CAST conversions between data types table is incorrect in Reference manual in some
VARCHAR and TIMESTAMP cases
> --------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-1804
>                 URL: http://issues.apache.org/jira/browse/DERBY-1804
>             Project: Derby
>          Issue Type: Bug
>          Components: Documentation
>    Affects Versions: 10.2.2.0
>            Reporter: Susan Cline
>         Assigned To: Laura Stewart
>
> The CAST function documentation contains a table which lists the explicit conversions
between data types.
> http://db.apache.org/derby/docs/10.2/ref/rrefsqlj33562.html
> For the 'SOURCE' values (the columns) of SMALLINT, INTEGER, BIGINT and DECIMAL the CAST
to VARCHAR is listed.  However, they should not be listed because this cast is not allowed.
 See the output below;
> ij> create table smallint_tab(id integer, col2 smallint);
> 0 rows inserted/updated/deleted
> ij> insert into smallint_tab values (1, 10);
> 1 row inserted/updated/deleted
> ij> select cast(col2 as varchar(10)) from smallint_tab;
> ERROR 42846: Cannot convert types 'SMALLINT' to 'VARCHAR'.
> Also from integer to varchar does not work: 
> ij> create table int_tab (id integer, col2 integer);
> 0 rows inserted/updated/deleted
> ij> insert into int_tab values (1, 10);
> 1 row inserted/updated/deleted
> ij> select cast(col2 as varchar(20)) from int_tab;
> ERROR 42846: Cannot convert types 'INTEGER' to 'VARCHAR'.
> Bigint neither: 
> ij> create table bigint_tab (id integer, col2 bigint); 
> 0 rows inserted/updated/deleted 
> ij> insert into bigint_tab values (1, 10); 
> ij> select cast(col2 as varchar(20)) from bigint_tab; 
> ERROR 42846: Cannot convert types 'BIGINT' to 'VARCHAR'. 
> Nor decimal: 
> ij> create table decimal_tab (id integer, col2 decimal); 
> 0 rows inserted/updated/deleted 
> ij> insert into decimal_tab values (1, 1.88); 
> 1 row inserted/updated/deleted 
> ij> select cast(col2 as varchar(3)) from decimal_tab; 
> ERROR 42846: Cannot convert types 'DECIMAL' to 'VARCHAR'. 
> The Cast from DATE to TIMESTAMP and TIME to TIMESTAMP also are not allowed, although
they
> are listed.  They need to be removed;
> ij> create table date_tab (id integer, col2 date);
> 0 rows inserted/updated/deleted
> ij> insert into date_tab values (1, CURRENT_DATE);
> 1 row inserted/updated/deleted
> ij> select cast(col2 as timestamp) from date_tab;
> ERROR 42846: Cannot convert types 'DATE' to 'TIMESTAMP'.
> ij> create table time_tab (id integer, col2 time);
> 0 rows inserted/updated/deleted
> ij> insert into time_tab values (1, CURRENT_TIME);
> 1 row inserted/updated/deleted
> ij> select cast(col2 as timestamp) from time_tab;
> ERROR 42846: Cannot convert types 'TIME' to 'TIMESTAMP'.

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